1/1/2024 0 Comments Lunar rockScientific relevance Īll six of the Apollo missions on which samples were collected landed in the central nearside of the Moon, an area that has subsequently been shown to be geochemically anomalous by the Lunar Prospector mission. These meteoroids remain in space longer, but eventually intersect the Earth's orbit and land. Some meteoroids ejected from the Moon get launched into orbits around the Sun. After leaving the Moon, most lunar meteoroids go into orbit around Earth and eventually succumb to Earth's gravity. Most left the Moon in the past 100,000 years. Ĭosmic-ray exposure history established with noble-gas measurements have shown that all lunar meteorites were ejected from the Moon in the past 20 million years. ![]() No source crater of lunar meteorites has been positively identified, although there is speculation that the highly anomalous lunar meteorite Sayh al Uhaymir 169 derives from the Lalande impact crater on the lunar nearside. Most lunar meteorites are launched from the Moon by impacts making lunar craters of a few kilometers in diameter or less. Lunar origin is established by comparing the mineralogy, the chemical composition, and the isotopic composition between meteorites and samples from the Moon collected by Apollo missions. None have yet been found in North America, South America, or Europe. All lunar meteorites have been found in deserts most have been found in Antarctica, northern Africa, and the Sultanate of Oman. The total mass is more than 190 kilograms (420 lb). As of July 2019, 371 lunar meteorites have been discovered, perhaps representing more than 30 separate meteorite falls (i.e., many of the stones are "paired" fragments of the same meteoroid). Several years later, Japanese scientists recognized that they had also collected a lunar meteorite, Yamato 791197, during the 1979 field season in Antarctica. Shortly thereafter, the meteorite now called Allan Hills 81005 was sent to Washington, DC, where Smithsonian Institution geochemist Brian Mason recognized that the sample was unlike any other known meteorite and resembled some rocks brought back from the Moon by the Apollo program. In January 1982, John Schutt, leading an expedition in Antarctica for the ANSMET program, found a meteorite that he recognized to be unusual.
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